Sound capture system for use within sound-generating devices

ABSTRACT

A sound capture system can include a sound capture device configured for placement within a sound-generating device. The sound capture system can include a suspension system configured to suspend the sound capture device within the sound-generating device. The suspension system acoustically decouples the sound capture device from the sound-generating device. The sound capture device includes a plurality of transducers configured to generate a plurality of audio signals concurrently from sound generated by the sound-generating device. In another aspect, the sound capture system includes a signal processing circuit.

TECHNICAL FIELD

This disclosure relates to a sound capture system adapted for use withina sound-generating device.

BACKGROUND

The sounds created by playing musical instruments may be capturedelectronically using transducers. A transducer such as a microphone maybe used to capture the sound generated by a musical instrument for anyof a variety of different purposes ranging from amplifying the capturedsounds in the case of a live performance to creating a sound recording.The traditional approach for capturing the sound generated by a musicalinstrument has been to place a microphone external to the musicalinstrument and near the musical instrument.

Certain classes of percussion instruments have a membrane that isstretched over or across some portion of the musical instrument. Aplayer strikes the membrane using one or more different techniques togenerate sound. One or more transducers are typically placed near themembrane to capture the sound generated by the musical instrument whenthe player strikes the membrane.

In some cases, a transducer may be placed inside of certain musicalinstruments such as a bass or “kick” drum of a drum set. Despite theplacement of the transducer relative to the musical instrument, thetransducer is typically held by a fixed or rigid mounting stand.

SUMMARY

In one or more example implementations, a system includes a soundcapture device configured for placement within a sound-generatingdevice. The system can include a suspension system configured to suspendthe sound capture device within the sound-generating device. Thesuspension system is capable of acoustically decoupling the soundcapture device from the sound-generating device. The sound capturedevice can include a plurality of transducers configured to generate aplurality of audio signals concurrently from sound generated by thesound-generating device.

In one aspect, the sound-generating device is a musical instrument. Forexample, the musical instrument can be a percussion instrument. In oneor more examples, the musical instrument has a stretched membrane. Forexample, the musical instrument may be a drum. In one or more examples,the musical instrument is a conga.

In another aspect, the sound capture device and the suspension systemare configured to retrofit within the sound-generating device.

In another aspect, the suspension system suspends the sound capturedevice within the sound-generating device so as to avoid physicalcontact of the sound capture device with an interior surface of thesound-generating device.

In another aspect, the sound capture device is encompassed by radiofrequency shielding.

In another aspect, the sound capture device includes at least one of aninner dust protective layer or an outer dust protective layer.

In another aspect, the suspension system includes an adjustable mountingsystem configured for retrofitting to existing hardware of thesound-generating device, wherein the hardware of the sound-generatingdevice is located within the sound-generating device.

In another aspect, the system can include a diffusor positioned belowthe sound capture device within the sound-generating device.

In another aspect, the diffusor can include a hollow body.

In another aspect, a plurality of prongs extend out from the hollowbody. The plurality of prongs are configured to contact an inner surfaceof the sound-generating device to prevent the hollow body fromcontacting the inner surface of the sound-generating device.

In another aspect, the sound capture device can include a firsttransducer configured to generate a first audio signal of the pluralityof audio signals. The sound capture device can include a secondtransducer configured to generate a second audio signal of the pluralityof audio signals.

In another aspect, the first transducer and the second transducer areradio-frequency noise-canceling transducers.

In another aspect, the first transducer is a first humbucking capsuleand the second transducer is a second humbucking capsule.

In another aspect, the first transducer and the second transducer areincluded in a transducer assembly that is suspended within the soundcapture device.

In another aspect, the first transducer and the second transducer arealigned along an axis forming an angle with a plane of a stretchedmembrane of the sound-generating device that is greater than 0° and lessthan 90°. For example, the angle may be approximately 45 degrees.

In another aspect, the system can include a signal processing circuitconfigured to receive the plurality of audio signals and generate anoutput audio signal from the plurality of audio signals.

In another aspect, the signal processing circuit includes a processorprogrammed to initiate executable operations.

In another aspect, the signal processing circuit includes a power supplyconfigured provide power to one or more active components of the signalprocessing circuit. The power supply is configured to derive the powerfrom a phantom power source coupled thereto.

In another aspect, the signal processing circuit includes a preamplifiercircuit configured to amplify a first audio signal of the plurality ofaudio signals generated by a first transducer of the plurality oftransducers and amplify a second audio signal of the plurality of audiosignals generated by a second transducer of the plurality oftransducers.

In another aspect, the signal processing circuit can include a phaseshift and attenuator circuit coupled to an output of the preamplifiercircuit. The phase shift and attenuator circuit is configured togenerate a phase-shifted version of the first audio signal by phaseshifting a first frequency range of the first audio signal byapproximately 180 degrees.

In another aspect, the phase shift and attenuator circuit is configuredto modify a level of at least one of the first audio signal or thesecond audio signal so that the first audio signal, as phase-shifted,and the second audio signal have substantially same levels.

In another aspect, the signal processing circuit can include adifference amplifier circuit configured to sum the first audio signaland the phase-shifted version of the second audio signal.

In another aspect, the signal processing circuit can include one or morefilter circuits coupled to an output of the difference amplifiercircuit. The one or more filter circuits are configured to attenuatefrequencies in a second frequency range and increase frequencies in oneor more other frequency ranges.

In another aspect, the one or more filter circuits can include ahigh-pass filter circuit configured to attenuate frequencies at or belowapproximately 60 Hz.

In another aspect, the one or more filter circuits can include ahigh-frequency boost filter circuit configured to increase frequenciesbetween approximately 3 kHz and approximately 10 kHz.

In another aspect, the one or more filter circuits can include amid-frequency boost filter circuit configured to increase frequenciesapproximately within the first frequency range of the phase shiftcircuit.

In another aspect, the signal processing circuit can include an outputstage including a transformer configured to generate the output signal.

In one or more example implementations, a musical instrument can includea shell having a stretched membrane. The musical instrument can includea sound capture device configured for placement within the shell. Themusical instrument can include a suspension system configured to suspendthe sound capture device within shell. The suspension system is capableof acoustically decoupling the sound capture device from the musicalinstrument. The sound capture device can include a plurality oftransducers configured to generate a plurality of audio signalsconcurrently from sound generated by the musical instrument.

In one aspect, the suspension system is adapted to retrofit the musicalinstrument with the sound capture device.

In another aspect, the musical instrument can include a diffusorpositioned below the sound capture device within the shell.

In another aspect, the diffusor can include a hollow body.

In another aspect, the diffusor can include a plurality of prongsextending out from the hollow body. The plurality of prongs areconfigured to contact an inner surface of the sound-generating device toprevent the hollow body from contacting the inner surface of thesound-generating device.

In another aspect, the musical instrument can include a signalprocessing circuit configured to receive the plurality of audio signalsand generate an output audio signal from the plurality of audio signals.

In another aspect, the signal processing circuit includes a processorprogrammed to initiate executable operations.

In one or more example implementations, a method can include providing asound capture device configured for placement within a sound-generatingdevice. The method can include providing a suspension system configuredto suspend the sound capture device within the sound-generating device.The suspension system is capable of acoustically decoupling the soundcapture device from the sound-generating device. The sound capturedevice can include a plurality of transducers configured to generate aplurality of audio signals concurrently from sound generated by thesound-generating device.

In another aspect, the method can include providing a signal processingcircuit configured to receive the plurality of audio signals andgenerate an output audio signal from the plurality of audio signals.

In another aspect, the signal processing circuit includes a processorprogrammed to initiate executable operations.

In another aspect, the method can include providing a diffusor withinthe sound-generating device.

In another aspect, the method can include installing the sound capturedevice within a musical instrument.

In another aspect, the installing retrofits the sound capture device tothe musical instrument.

In another aspect, the method can include installing the sound capturedevice and the signal processing circuit within the musical instrument.

In one or more example implementations, a method can include generatinga first differential signal from a first transducer disposed in amusical instrument. The method can include generating a seconddifferential signal from a second transducer disposed in the musicalinstrument. The method can include generating a first composite signalfrom the first differential signal. The method can include generating asecond composite signal from the second differential signal. The methodcan include signal processing the first composite signal and the secondcomposite signal using signal processing circuitry to generate an audiooutput signal by, at least in part, taking a difference between thefirst composite signal and the second composite signal.

In another aspect, the signal processing can include filtering adifference signal generated by the taking a difference between the firstcomposite signal and the second composite signal using one or morefilter circuits.

In another aspect, the method can include providing power to one or moreactive components of a signal processing circuit configured to performthe signal processing, wherein the power is derived from a phantom powersource.

This Summary section is provided merely to introduce certain conceptsand not to identify any key or essential features of the claimed subjectmatter. Other features of the inventive arrangements will be apparentfrom the accompanying drawings and from the following detaileddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

The inventive arrangements are illustrated by way of example in theaccompanying drawings. The drawings, however, should not be construed tobe limiting of the inventive arrangements to only the particularimplementations shown. Various aspects and advantages will becomeapparent upon review of the following detailed description and uponreference to the drawings.

FIG. 1 illustrates certain operative features of an example soundcapture system.

FIG. 2 illustrates example attachment points for use with a suspensionsystem adapted to suspend a sound capture device within asound-generating object.

FIG. 3 illustrates an example of a suspension system used to suspend asound capture device within a sound-generating object.

FIG. 4 illustrates an overhead view of a sound-generating object with anexample sound capture device suspended therein.

FIGS. 5A and 5B illustrate certain operative features of an examplesound capture device.

FIG. 6 illustrates an example of certain structural features of a soundcapture device.

FIG. 7 illustrates another example of a sound capture device withshielding and protective covering(s) removed.

FIG. 8 illustrates an example of a transducer assembly.

FIG. 9 illustrates an example of a transducer assembly disposed within aframe structure of a sound capture device.

FIG. 10 illustrates an example orientation of a transducer assemblydisposed within a sound-generating object.

FIGS. 11A, 11B, and 11C illustrate example vibration modes of astretched membrane of a percussion instrument.

FIGS. 12A and 12B illustrate example diffusors.

FIG. 13 illustrates an exploded view of an example sound capture systemand musical instrument.

FIG. 14 illustrates an example signal processing circuit.

FIG. 15 is a graph illustrating an example of a phase curve applied by aphase shift portion of a phase shift and attenuator circuit of thesignal processing circuit.

FIG. 16 is a graph illustrating an example of a notched frequency arounda center frequency that may be generated by the signal processingcircuit.

FIG. 17 illustrates an example spectrum analysis of the sound of a tumbaconga drum as captured by a conventional microphone located external tothe drum.

FIG. 18 illustrates an example spectrum analysis of the sound of a tumbaconga drum as captured by a single transducer.

FIG. 19 illustrates an example spectrum analysis of a signal as outputfrom the sound capture system in accordance with the inventivearrangements.

FIG. 20 is a block diagram illustrating an example of the connectivitybetween the sound capture device and the signal processing circuit.

FIG. 21 is a circuit diagram illustrating an example preamplifiercircuit of the signal processing circuit.

FIG. 22 is a circuit diagram illustrating examples of a phase shift andattenuator circuit, a difference amplifier circuit, and a high-passfilter described in connection with FIG. 14 .

FIG. 23 is a circuit diagram illustrating examples of a high-frequencyboost filter and a mid-frequency boost filter described in connectionwith FIG. 14 .

FIG. 24 is a circuit diagram illustrating an example of an audio outputcircuit described in connection with FIG. 14 .

FIG. 25 is a circuit diagram illustrating an example of a power supplyas described in connection with FIG. 14 .

FIG. 26 is a circuit diagram illustrating examples of an audio outputcircuit and a transformer in relation to a power supply as described inconnection with FIG. 14 .

FIG. 27 illustrates another example implementation of selectedcomponents of the signal processing circuit described in connection withFIG. 14 .

FIG. 28 illustrates an example method for a sound capture system inaccordance with the inventive arrangements described herein.

FIG. 29 illustrates an example method illustrating certain operativefeatures of the inventive arrangements described herein.

DETAILED DESCRIPTION

While the disclosure concludes with claims defining novel features, itis believed that the various features described within this disclosurewill be better understood from a consideration of the description inconjunction with the drawings. The process(es), machine(s),manufacture(s) and any variations thereof described herein are providedfor purposes of illustration. Specific structural and functional detailsdescribed within this disclosure are not to be interpreted as limiting,but merely as a basis for the claims and as a representative basis forteaching one skilled in the art to variously employ the featuresdescribed in virtually any appropriately detailed structure. Further,the terms and phrases used within this disclosure are not intended to belimiting, but rather to provide an understandable description of thefeatures described.

This disclosure relates to a sound capture system adapted for use withina sound-generating device. In one aspect, the sound-generating device isa musical instrument. In accordance with the inventive arrangementsdescribed within this disclosure, example implementations of soundcapture systems are provided that utilize a sound capture device. Thesound capture device may be disposed within the sound-generating device.In one or more example implementations, the sound capture device issuspended within the sound-generating device. The sound capture deviceis capable of translating sound waves generated by the sound-generatingdevice into audio signals that may be output to other systems foramplification, mixing, recording, signal processing, or other purposes.

In one or more example implementations, the sound capture systemincludes a signal processing circuit. The signal processing circuit iscapable of receiving audio signals generated by the sound capturedevice. The signal processing circuit is capable of performing varioussignal processing operations on the audio signals from the sound capturedevice. The signal processing circuit generates, from the audio signals,a processed audio signal. The processed audio signal generated by thesignal processing circuit, also referred to herein as the “outputsignal,” may be output or provided to one or more other systems ordevices.

For purposes of simplicity and clarity of illustration, elements shownin the figures have not necessarily been drawn to scale. For example,the dimensions of some of the elements may be exaggerated relative toother elements for clarity. Further, where considered appropriate,reference numbers are repeated among the figures to indicatecorresponding, analogous, or like features.

FIG. 1 illustrates an example implementation of a sound capture system100. In the example of FIG. 1 , sound capture system 100 includes asound capture device 102 and a signal processing circuit 104. In theexample, the sound-generating device is a musical instrument 106.Musical instrument 106 is shown having a portion cutaway (e.g., cutaway108). Cutaway 108 is for purposes of illustration only to better depictthe position of sound capture device 102 and signal processing circuit104 within musical instrument 106. In normal or regular operation,musical instrument 106 will not have or include any cutaways. Throughcutaway 108, sound capture device 102 is visible as being disposedwithin musical instrument 106. Sound capture device 102 includes one ormore transducers that capture sound generated by musical instrument 106.Through cutaway 108, a diffusor 112 is visible. Diffusor 112 isoptionally included as part of sound capture system 100 within musicalinstrument 106.

In one or more example implementations, musical instrument 106 is apercussion instrument. In the example, musical instrument 106 is a classof percussion instrument having a membrane stretched across some portionof the musical instrument. In an example implementation, musicalinstrument 106 is a conga. Other examples of different types of musicalinstruments with which the inventive arrangements may be used include,but are not limited to, kick drums, snare drums, tom-toms, floor toms,timbales, caixa, repique, surdo, taiko, thammattama, timpani, urumi,zabumba, bongos, congas, batá, barriles (bomba), cajón, dholak, djembe,doumbek, kpanlogo, mridangam, sabar, and/or tabla. It should beappreciated that the inventive arrangements described within thisdisclosure may be used within any of a variety of different musicalinstruments including different types of percussion instruments such aspercussion instruments having stretched membranes. For example, soundcapture system 100 may be used with any of a variety of different typesof drum. In other arrangements, sound capture system 100 may be usedwith other varieties of sound-generating devices.

In the example of FIG. 1 , musical instrument 106 includes a shell 114having a drumhead 116. Drumhead 116 is an example of a stretchedmembrane. Drumhead 116 is held in place by a rim 118 having a pluralityof tab portions 122. In the example, tuning lugs 128 may have one endthat is hooked onto an aperture in the tab portion 122 and another endthat is threaded to engage a tuning bracket 124. A fastener such as anut may prevent each tuning lug 128 from disengaging from tuning bracket124.

In the example, tuning brackets 124 are coupled to shell 114 by way offasteners such as bolts that extend through shell 114 beyond the innersurface of shell 114. In the example of FIG. 1 , two bolts are used tocouple tuning brackets 124 to shell 114. The bolts may be threaded.Musical instrument 106 may have a number of tuning brackets 124 thatdepends on the size, e.g., circumference, of shell 114 and/or drumhead116. For purposes of illustration, musical instrument 106 may have 5 or6 tuning brackets where shells and/or drumheads with largercircumferences typically have a larger number of tuning brackets thanthose with smaller circumferences.

Sound capture device 102 is communicatively linked to signal processingcircuit 104. In one aspect, signal processing circuit 104 may be mountedto the inner surface of shell 114. In other example implementations,signal processing circuit 104 may be mounted to an outer surface ofshell 114. In still other example implementations, signal processingcircuit 104 need not be mounted or affixed to shell 114 or to musicalinstrument 106 at all.

In the example of FIG. 1 , signal processing circuit 104 has an outputcoupled to an audio connector 130. In an example implementation, audioconnector 130 is a standard XLR connector. Use of an XLR connectorallows electrical power to be supplied to signal processing circuit 104by way of “phantom power.” Phantom power refers to the +48 volts of DCpower that may be provided through XLR cables by certain types ofmusical equipment (e.g., mixing consoles, preamplifiers, audiointerfaces, etc.) to other audio equipment such as certain types ofmicrophones. In this example, signal processing circuit 104 is poweredby phantom power. Though audio connector 130 is described as an XLRconnector, it should be appreciated that other types of connectors maybe used and that use of an XLR connector is not intended to be alimitation of the inventive arrangements. Still, use of an XLR connectorprovides wide-ranging compatibility and connectivity of sound capturesystem 100 with other music and/or sound equipment.

In the example, audio connector 130 may be mounted in shell 114. Inother examples, audio connector 130 may be included as part of signalprocessing circuit 104, e.g., disposed in or built into the housing ofsignal processing circuit 104. In another example, audio connector 130may be located at the end of a cable that extends out from signalprocessing circuit 104 through the bottom or open portion of musicalinstrument 106. The particular manner in which signal processing circuit104 and/or audio connector 130 are coupled to sound capture device 102and/or to the musical instrument 106 is not intended to be limiting.

In the example, sound capture device 102 is suspended within musicalinstrument 106. Sound capture device 102 may be suspended within musicalinstrument 106 using a suspension system. Suspension of sound capturedevice 102 acoustically decouples sound capture device 102 from musicalinstrument 106. As defined within this disclosure, the term“acoustically decouple” means that sound capture device 102 is not inphysical contact with musical instrument 106. In the example, soundcapture device 102 couples to musical instrument 106 via a non-rigidstructure such as the suspension system. Sound capture device 102 isheld in place using the suspension system. Being acoustically decoupled,sound capture device 102 is suspended from attachment points withinmusical instrument 106 without using rigid connectors.

Suspension of sound capture device 102 within musical instrument 106provides a variety of benefits over other conventional techniques forusing transducers such as microphones with musical instruments and, inparticular, percussion instruments having a stretched membrane. In oneaspect, suspension of sound capture device 102 within musical instrument106 provides improved acoustic isolation between musical instrument 106and other adjacent or companion instruments. For example, drums areoften played in pairs or sets. Congas, for example, are often played inpairs. Other types of drums are played in larger sets such as a drum kitor a trap kit. Inclusion of sound capture device 102 within musicalinstrument 106 helps to prevent sound capture device 102 from detectingand capturing sounds emanating from other sound sources that are nearbyor proximate to musical instrument 106 including other percussioninstruments, ambient noise such as wind, and the like. The improvedisolation improves the overall quality of the sound captured by soundcapture device 102.

Sound capture system 100 and/or sound capture device 102 may be used asa replacement for convention microphones including microphones typicallymounted on or around the exterior of the musical instrument. Such otherconventional microphones are often positioned above or adjacent to thestretched membrane of the percussion instrument and mounted using standsor clamps. As such, conventional microphones are unable to provide thelevel of isolation achieved using sound capture system 100. Moreover,ideal placement of conventional microphones for capturing soundgenerated by a stretched membrane musical instrument is approximately 1inch above the stretched membrane with approximately a 45-degree anglerelative to the plane of the stretched membrane. This microphonepositioning, however, often gets in the way of the musician'shands/sticks/mallets and/or otherwise hinders the playing of the musicalinstrument. Sound capture system 100 and/or sound capture device 102does not hinder playing of the musical instrument.

Sound capture system 100 provides other benefits over conventionalmicrophones. Sound capture system 100, when used with percussioninstruments as described herein, does not obstruct the audience's viewof the player, instrument, or other objects on-stage. Because soundcapture system 100 need not be removed from musical instrument 106 onceinstalled, the amount of time devoted to microphone placement and setupfor live playing and/or recording may be significantly reduced. Further,the placement of sound capture device 102, once properly adjusted withinmusical instrument 106, need not be adjusted. This also allows themusician playing musical instrument 106 to reposition musical instrument106 while playing without having to reposition sound capture system 100or sound capture device 102. Because sound capture device 102 remains inplace while musical instrument 106 is moved, whether during transport oronstage during a performance, for example, sound capture system 100 iscapable of providing a consistent frequency response and signal leveldespite movement of musical instrument 106 during use.

Diffusor 112 has a body portion that is hollow and placed inside musicalinstrument 106. In one or more example implementations, the body portionof diffusor 112 is formed or made of a rigid material such as plastic orcardboard. The body portion of diffusor 112 may be wrapped with alow-density foam, insulation, or sound-absorbing material. Diffusor 112may include prongs capped with feet that keep diffusor 112 in place. Thefeet, for example, may be implemented using rubber or neoprene. In oneaspect, the body portion of diffusor 112 may be cylindrical in shape. Inanother aspect, the body portion of diffusor 112 may be contoured suchthat diffusor 112 is widest at the top (e.g., toward drumhead 116) andtapers or narrows toward the bottom (e.g., the opposite end of musicalinstrument 106 from drumhead 116). The prongs serve to physicallydecouple diffusor 112 from the inner surface of musical instrument 106so as to not dampen the sound of musical instrument 106. The feetprevent the diffusor 112 from moving and also prevent the prongs, e.g.,which may be implemented using metal, from rattling or making otherundesirable noises.

Optionally, cords may be used in conjunction with the prongs to keepdiffusor 112 in place. The cords may be made of elastic, bungee, orother stretchable material. These cords may be coupled to fasteningpoints within the shell 114 and provide enough tension to maintain thediffusor 112 in position even in cases where musical instrument 106 ismoved and/or transported.

Diffusor 112 is capable of acting as a diffusor and/or absorber ofstanding waves that may build up within musical instrument 106, e.g., inthe narrower and tapered section of musical instrument 106. Diffusor 112is hollow to allow air to flow freely through musical instrument 106.The shape of the body portion of diffusor 112 is suited to mitigatingstanding waves as the sound generated by musical instrument 106 bouncesoff of the inner walls of a conical enclosure (e.g., inner portion ofshell 114) in more complex patterns compared to using a square bafflethat would not adequately diffuse the standing wave.

FIG. 1 illustrates an example implementation where sound capture system100 may be added to an existing musical instrument after manufacture.For example, sound capture system 100 may be retrofitted to existingmusical instruments. That is, sound capture system 100 may be added toan existing musical instrument in the field. In other exampleimplementations, sound capture system 100 may be added or included witha musical instrument as part of the manufacturing process, e.g., at thetime of manufacture.

Sound capture system 100 provides other benefits compared toconventional microphones placed inside of a stretched membranepercussion instrument. For example, conventional microphones aredifficult to mount within stretched membrane percussion instruments.Making electrical and/or audio connections with conventional microphonesmounted within stretched membrane percussion instruments is oftenimpractical.

In addition, a conventional microphone is susceptible to capturing aprimary standing wave inside the musical instrument that manifests as anoffending frequency referred to herein as an “artifact” in the capturedaudio. In general, the artifact is determined by the dimensions of theinterior volume of the musical instrument and the material of themusical instrument. In many cases, a conventional microphone issusceptible to reverberation occurring within the musical instrumentthat translates into other artifacts in the form of unwanted overtonesor unwanted emphasis of certain overtones in the audio spectrum.Conventional microphones are also susceptible to another type ofartifact referred to as a “Helmholtz resonance” that is attributed tothe tubular design of certain stretched membrane percussion instruments.The Helmholtz resonance translates into a significant amount of lowfrequency energy, where the particular frequencies are determined by theparticular length and geometry of the musical instrument.

FIG. 2 illustrates example attachment points that engage with thesuspension system for suspending sound capture device 102 within musicalinstrument 106. In the example, bolts 206 mount tuning bracket 124 tothe outside of shell 114 extend past inner surface 202 of shell 114. Inthe example, bolts 206 pass through a plate 204. Ends of bolts 206 maybe threaded so that a nut and washer may be engaged to maintain tuningbracket 124 securely coupled to the outer surface of shell 114. In theexample, plate 204-1 and bolts 206-1 illustrate a conventional mountingof a tuning bracket 124. That is, tuning bracket 124, bolts 206, andplate 204 are part of the standard equipment of a stretched membranetype of percussion instrument.

In the example of FIG. 2 , plates 204-1, 204-2, and 204-3 are visible.Plate 204-2 and bolts 206-2 along with plate 204-3 and bolts 206-3illustrate example attachment points from which universal mountingassemblies 212 may be attached. Each of the universal mountingassemblies 212 is considered part of the suspension system for soundcapture device 102. Each universal mounting assembly 212 may include aspacer 214 for each bolt 206 (e.g., 2 spacers 214 per mounting assembly)and a universal mounting plate 218. In one aspect, each spacer 214 maybe implemented as a hollow pin that is threaded on the inner surface ateach end to receive complementary threaded bolts or fasteners. Forexample, each spacer 214 may be threaded within the inner surface oneach end to engage a respective bolt 206 on a first end and another bolt216 on the other end. Bolts 216 secure universal mounting plate 218 tospacers 214 and to shell 114.

FIG. 2 also illustrates a C-mount 220 that is fastened to universalmounting assembly 212. C-mount 220 is also a part of the suspensionsystem for sound capture device 102. For purposes of illustratinguniversal mounting assembly 212, one C-mount 220 is illustrated. Itshould be appreciated that each universal mounting assembly 212 willhave a C-mount 220 coupled thereto. C-mount 220 is generally shaped as aletter “C” with a top leg that is parallel to a bottom leg and with thelegs joined by a spine portion perpendicular to each leg. Each leg mayinclude a plurality of apertures 226 that may be used to suspend soundcapture device 102.

C-mount 220 may have a slot 222 within the spine portion through which afastener such as bolt 224 may pass. Bolt 224 may pass through a selectedaperture 219 of universal mounting plate 218 and engage a nut to secureC-mount 220 to universal mounting plate 218. As illustrated, C-mount 220may be adjusted in a direction along an axis (e.g., vertically) that issubstantially perpendicular to the plane of drumhead 116, e.g., alongthe axis defined by universal mounting plate 218. Bolt 224 may beloosened so that C-mount 220 may be moved up and down (e.g., adjusted)along the length of slot 222 to a desired position, whereby bolt 224 maybe tightened to hold C-mount 220 in place.

In one or more example implementations, sound absorbing material may beapplied to C-mounts 220. As an illustrative example, small foam panelsmay be adhered to C-mounts 220. The sound absorbing material is capableof reducing higher frequency reverberations that may emanate neardrumhead 116. These higher frequency reverberations sound metallic andunpleasant in nature. The sound absorbing material is capable ofabsorbing these higher frequency reverberations while not dampening theoverall sound of musical instrument 106.

In one aspect, the length of spacers 214 may be varied to account forthe curvature of inner surface 202 of shell 114 such that universalmounting plate 218 is perpendicular to the plane of drumhead 116. Thatis, the length of spacers 214 for a same universal mounting plate 218may be different so that universal mounting plate 218 is perpendicularto drumhead 116 depending on the contour of inner surface 202 of shell114.

As illustrated in the example of FIG. 2 , the hardware added to theinside of musical instrument 106 for suspending sound capture device 102therein is adjustable and is adapted to the existing hardware of musicalinstrument 106. The hardware takes advantage of existing hardware, e.g.,bolts, that are accessible on the inside and outside of musicalinstrument 106.

C-mount brackets 218 are attached to spacers 214. As noted, spacers 214are coupled to the existing hardware of musical instrument 106. Soundcapture device 102 may be mounted at a selected and variable distancefrom the inner surface 202 of shell 114 based on the length of spacers214 and the size of sound capture device 102. Further, the length ofspacers 214 allow universal mounting plate 218 to be mountedsubstantially vertically despite the curvature of inner surface 202. Itshould be appreciated that the hardware illustrated in FIG. 2 may beformed or machined for compatibility with specific instrument brands,makes, and/or models. In other examples, a “universal” mounting kit maybe used across a plurality of different instrument brands, makes, and/ormodels.

Attaching the C-mounts 220 to C-mount brackets 218 allows C-mounts 220,and thus sound capture device 102, to be raised or lowered withinmusical instrument 106. In one aspect, C-mounts 220 may be attached tosound capture device 102 first and then attached to C-mount brackets 218by way of bolts 224. This allows sound capture device 102 lowered intomusical instrument 106 and affix sound capture device 102 to the musicalinstrument 106 with a single attachment point (e.g., one bolt 224) oneach side as shown in FIG. 7 . Raising moves sound capture device 102closer to drumhead 116 (e.g., closer to the top of musical instrument106), while lowering moves sound capture device 102 farther away fromdrumhead 116 (closer to the bottom of musical instrument 106). Differentapertures 226 in the horizontal legs of C-mounts 220 allow sound capturedevice 102 to be moved side-to-side in the plane of drumhead 116 toensure that sound capture device 102 does not contact inner surface 202.

In general, universal mounting assembly 212 and the attached C-mounts220 may be implemented with a low profile while still maintaining thestructural integrity necessary to withstand stress from a dynamic load,which is sound capture device 102 suspended therefrom. The adjustabilityof universal mounting assembly 212 and the attached C-mounts 220 in thehorizontal (parallel to drumhead 116) and vertical (perpendicular todrumhead 116) directions allow sound capture device 102 to be positionedwithin the musical instrument 106 based on the shape of musicalinstrument 106 and the position of existing hardware of musicalinstrument 106 to ensure consistent transducer placement.

FIG. 3 illustrates an example of the suspension system used to suspendsound capture device 102 within musical instrument 106. In the exampleof FIG. 3 , sound capture device 102 is visible within musicalinstrument 106 though cutaway 108. The suspension system, which includestwo universal mounting assemblies 212, each with a C-mount 220 attachedthereto, is used to suspend sound capture device 102 within musicalinstrument 106. In the example, sound capture device 102 is suspendedusing a plurality of cords 302, which are considered part of thesuspension system for the sound capture device. Cords 302 may be formedof a stretchable or flexible material. In one or more exampleimplementations, cords 302 may be implemented using a stretchablematerial such as bungee cord. In one or more other exampleimplementations, cords 302 may be implemented using rubber, elastic,and/or other stretchable and/or resilient materials. In one or moreexample implementations, cords 302 may be implemented with any of avariety of cross-sectional shapes such as circular, oval, rectangular,square, etc.

FIG. 4 illustrates an overhead view of musical instrument 106 with soundcapture device 102 suspended therein using the suspension system. In theexample of FIG. 4 , drumhead 116 and rim 118 are removed from musicalinstrument 106 to expose the interior of musical instrument 106. In theexample of FIG. 4 , sound capture device 102 is suspended using thesuspension system comprising two universal mounting assemblies 212, eachhaving a C-mount 220 attached thereto, and using cords 302. Asillustrated in the example, one (or more) tuning brackets may bedisposed between the two tuning brackets 124 to which the universalmounting assemblies 212 are coupled.

In the example, cords 302 suspend sound capture device 102 from C-mounts220. In the example, sound capture device 102 is coupled to the topportion (e.g., leg) of each C-mount 220 using one cord 302 loopedthrough an aperture 226 of the top leg. Sound capture device 102 is alsocoupled to the bottom portion (e.g., leg) of each C-mount 220 using onecord 302 looped through an aperture 226 of the bottom leg. In theexample, a total of 4 cords 302 are used to suspend sound capture device102 within the interior portion of musical instrument 106. Asillustrated, ends of the cords 302 may be knotted or knotted around anobject to prevent the cords from being pulled out of the aperturesthrough which cords 302 were drawn.

In one or more example implementations, sound capture device 102 issuspended using cord 302 having sufficient strength and tension so as toprevent sound capture device 102 from contacting any interior surface ofshell 114, the under-side of drumhead 116, universal mounting assembly212, C-mount 220, or other portion of musical instrument 106. Thisprevents unwanted rattling, noise, or vibrations when musical instrument106, with sound capture device 102 suspended therein, is shakenvigorously as may occur during a theatrical and/or lively liveperformance. Certain performers, for example, Ray Barreto, were knownfor their lively conga performances. The suspension of sound capturedevice 102 within musical instrument 106, for example, may withstand thevigorous shaking of musical instrument 106 that may occur to avoidgenerating unwanted audio artifacts from sound capture device 102contacting any of the various surfaces described.

FIG. 5A illustrates certain operative features of sound capture device102. In the example of FIG. 5A, sound capture device 102 is wrapped in,or encompassed by, shielding 502. Shielding 502 may be a metallic meshthat provides electromagnetic (e.g., radio-frequency or RF) shieldingfor the transducer assembly located therein. As shown, sound capturedevice 102 has an outer frame 602 that is formed of an upper frame strap506, a lower frame strap 508, and a plurality of outer supports 510 thatare arranged perpendicular to frame rings 506, 508. In the example,upper frame strap 506 includes four tabs 512 to which cords 302 attach(e.g., are pulled through). In one or more examples, a pair of tabs 512may be coupled to an aperture 226 of C-mount 220 by a cord 302. In suchan example, sound capture device 102 is suspended using the suspensionsystem using 4 cords 302. In another example, each tab 512 may becoupled to an aperture 226 of C-mount 220 by an independent cord 302. Inthe latter case, sound capture device 102 is suspended using thesuspension system using 8 cords 302.

In one or more other examples, the suspension system may include morethan 2 universal mounting assemblies with attached C-mounts 220. Forexample, 3 or 4 such universal mounting assemblies may be used whereeach has an attached C-mount 220 and each is coupled to sound capturedevice 102 by one or more cords 302. In this regard, the number ofuniversal mounting assemblies with attached C-mounts used to suspendsound capture device 102 is not intended as a limitation so long assound capture device 102 is prevented from contacting the inner portionof shell 114 or other components located within musical instrument 106.Further, it should be appreciated that the number of cords 302 used tosuspend sound capture device 102 within musical instrument 106 from eachuniversal mounting assembly and attached C-mount is not intended to belimiting. For example, on each leg of C-mount 220, one, two, or morecords 302 may be used to suspend sound capture device 102.

In the example of FIG. 5A, each of bolts 224 may serve as a single pointof contact or connection between sound capture device 102 and eachuniversal mounting assembly 212.

In another aspect, in addition to shielding 502, a further protectivelayer may be included and used to wrap sound capture device 102 toprevent dust from entering the inside of sound capture device 102. Thefurther protective layer (not shown) may be implemented as a clothand/or mesh. The further protective layer may be stretchable and withinthe shielding 502. In another example implementation, a secondprotective layer for dust may be external to shielding 502. In stillanother example implementation, one or more such protective layers maybe included inside of shielding 502, outside of shielding 502, or bothinside and outside of shielding 502. The further protective layer orlayers, as the case may be, are capable of providing additional acousticdampening properties that reduce transients that may occur when musicalinstrument 106 is struck. Such transients may generate significantvoltages that, in some cases, if not dampened as described, may overloadcertain portions of signal processing circuit 104.

FIG. 5B illustrates certain operative features of sound capture device102. In the example of FIG. 5B, sound capture device 102 includes a topsection and a bottom lid 520. In the example, sound capture device 102is inverted or upside-down so that bottom lid 520 is showing and the topsection is hidden from view. The top section and bottom lid may bewrapped or covered as described in connection with FIG. 5A. That is, thetop section and bottom lid may be covered with shielding 502, and one ormore further protective layers (e.g., dust covers) that may be locatedinside of shielding 502, outside of shielding 502, or both inside andoutside of shielding 502. In the example of FIG. 5B, top lid 520 isfitted with a multi-pin connector 522 (e.g., an audio connector) that isconnected to the transducers included within sound capture device 102.In the example, multi-pin connector 522 is a 5-pin connector. Whensuspended within musical instrument 106, multi-pin connector 522 may beoriented downward toward the ground to provide signals generated by thetransducers included in sound capture device 102 to signal processingcircuit 104.

FIG. 6 illustrates an example implementation of certain structuralfeatures of sound capture device 102. In the example, shielding 502 andany dust covers have been removed to better illustrate structuralaspects of sound capture device 102. In the example, sound capturedevice 102 includes outer frame 504 and an inner frame 602. Inner frame602 is formed of an upper frame ring 604, a lower frame ring 606, and aplurality of inner supports 608 arranged perpendicular to frame rings604, 606. In general, upper frame ring 604 is concentric with upperframe strap 506. Upper frame ring 604 and upper frame strap 506 may beattached using a plurality of fasteners. Lower frame ring 606 isconcentric with lower frame strap 508. Lower frame ring 606 and lowerframe strap 508 may be attached using a plurality of fasteners. Innersupports 608 may be aligned with outer supports 510. Outer supports 510may be attached to upper frame strap 506 and lower frame strap 508 asshown. Inner supports 608 may be attached to upper frame ring 604 andlower frame ring 606 as shown. In one aspect, shielding 502 and theadditional protective layers may be disposed between inner frame 602 andouter frame 504.

In the example of FIG. 6 , elements of outer frame 504 such as upperframe strap 506, lower frame strap 508, the plurality of outer supports510, and tabs 512 are shown in greater detail. In the example, upperframe strap 506 and lower frame strap 508 each has four tabs 512 towhich cords 302 attach. The engagement of cords 302 to tabs 512 can beseen where cords 302 are looped and extend through a hole or aperture oftabs 512. In the example of FIG. 6, 4 cords 302 are used to suspendsound capture device 102. As noted, in other example implementations, adifferent number of cords 302 may be used. For example, each tab 512 maybe coupled to an aperture 226 of C-mount 220 by a cord 302. The cord 302may be drawn through an aperture 226 of C-mount 220 and secured using apin or other mechanism that prevents cord 302 from becoming disengagedfrom aperture 226.

In the example of FIG. 6 , each of two I-connectors 610 is coupled to adifferent inner support 608 of inner frame 602. Inner supports 608 towhich the !-connectors 610 attach are disposed at opposing ends of adiameter of upper and/or lower frame rings 604, 606. Each I-connector610 includes a stem 612 and two edges 614 arranged perpendicular to stem612. In the example, stems 612 are rotatably coupled to inner supports608 via a connector 616. In an example, each connector 616 may be athreaded bolt with a fastener such as a nut configured to engage thethreaded bolt. The connector 616 that is closer in the perspective viewis obscured by outer support 510. Each I-connector 610 is capable ofrotating around the axis defined by the connector 616. Each I-connector610 may be adjusted to a desired position with connector 616 beingtightened to maintain the respective I-connector 610 in the desiredposition.

Inner frame 602 and outer frame 504 maybe formed of the same ordifferent material. In one example, outer frame 504 may be formed ofmetal, while upper and lower frame rings 604, 606 are formed of plasticsuch as polyvinyl chloride (PVC). In the examples illustrated herein,outer supports 510, 608 may be formed of metal or another material ofsuitable strength to support suspension of the transducer assembly 702therefrom.

For purposes of description, inner frame 602 and outer frame 504 ofsound capture device 102 may be referred to collectively as the “framestructure” of sound capture device 102. In one or more otherembodiments, however, the frame structure may be implemented as aunified structure rather than including an inner frame and an outerframe. The inventive arrangements are not intended to be limited to aframe structure having both an inner frame 602 and an outer frame 504.

FIG. 7 illustrates another example implementation of sound capturedevice 102 with shielding 502 and protective covering(s) removed. Soundcapture device 102 includes a transducer assembly 702 disposed therein.Within sound capture device 102, transducer assembly 702 is suspendedusing an inner suspension system that attaches to the frame structure ofsound capture device 102. The inner suspension system may include theI-connectors 610 of FIG. 6 . In general, transducer assembly 702 issuspended from an I-connector 610 on each end. Transducer assembly 702may be suspended from inner frame 602, e.g., from I-connectors 610, byway of a plurality of inner cords 704 similar to the manner in whichsound capture device 102 is suspended within musical instrument 106using the suspension system with cords 302 as previously described. Thesuspension of transducer assembly 702 using inner cords 704 incombination with cords 302 creates a double suspension system fortransducer assembly 702, where the double suspension system is formed ofthe suspension system used to suspend sound capture device 102 (e.g., anouter suspension system) and the inner suspension system used to suspendtransducer assembly 702 within sound capture device 102.

FIG. 8 illustrates an example implementation of transducer assembly 702.In the example, transducer assembly 702 is coupled to an I-connector 610on each edge by cords 704. Transducer assembly 702 includes twotransducer housing blocks 802, with each transducer housing block 802having a transducer 804 securely disposed therein.

In one or more example implementations, each transducer 804 may behardened with respect to electromagnetic interference. For example, eachof transducers 804 may be implemented as a humbucking microphonecapsule. The humbucking microphone capsules used may be parts that arecommercially available. A humbucking microphone capsule includes aprimary coil that is configured to function as a microphone element tocapture audio, e.g., sound waves. The primary coil also captureselectromagnetic interference (EMI). The humbucking microphone capsuleincludes a secondary coil that is not configured to capture audio, butrather capture only EMI. The two coils are wired in series with theprimary coil and the secondary coil being 180 degrees, or substantially180 degrees, out of phase so that the EMI cancels out leaving the audiosignal as an output. The EMI is unwanted as the EMI can create audiblenoise artifacts including, but not limited to, 60 cycle hum in the audiooutput signal.

In the example of FIG. 8 , each of transducers 804 includes a primarycoil (not shown) that is configured to capture audio and electromagneticinterference and a secondary or “noise” coil 808 that is configured todetect electromagnetic interference, but no audio. Due to the viewingangle of FIG. 8 , only one secondary coil is visible as part of thehumbucking microphone capsules. It should be appreciated, however, thateach transducer 804, e.g., implemented as a humbucking microphonecapsule, includes both a primary coil and a secondary coil 808.

Transducers 804 may be implemented in any of a variety of differentsizes. It should be appreciated that larger sized transducers 804 (e.g.,humbucking microphone capsules having coils with larger diameters) maybe capable of capturing lower frequencies with greater fidelity. Forpurposes of illustration, in the example of FIG. 8 , each transducer 804has a diameter of 1.25 inches. It should be appreciated, however, thatdifferent sized transducers may be used. In the example of FIG. 8 ,transducers 804 are matched (e.g., are the same).

In one or more examples, each transducer 804 may be implemented using ahousing, e.g., a plastic or metal housing. The housing may becylindrical and include a moving diaphragm that is attached to theprimary coil. Movement of the diaphragm from changing sound pressurelevels causes the primary coil to move with respect to a fixed magnetthereby inducing current. Secondary coil 808 is wired in series with theprimary coil, where the orientation of the windings of secondary coil808 are placed out-of-phase with the windings of the primary coil. Theprimary coil and secondary coil 808 may be wired 180 degrees, orsubstantially 180 degrees, out of phase so that the electromagneticinterference is canceled. As noted, in one or more examples, eachtransducer 804 may be implemented using any of a variety of commerciallyavailable humbucking microphone capsules.

In one or more example implementations, each transducer housing block802 may be formed of an acoustically inert material. In an example, eachtransducer housing block 802 is formed of wood. In another example, eachtransducer housing block 802 is made from a plastic material. An exampleplastic material that may be used to implement transducer housing blocks802 is a plastic polymer such as polyvinyl chloride or “PVC.”

Each transducer 804 may couple to signal processing circuit 104 via aplurality of conductors or wires. Signal processing circuit 104 maycouple to each transducer 804 via a positive conductor, a negativeconductor, and ground conductor, where the ground conductors of bothtransducers 804 are coupled together forming a common ground. Signalprocessing circuit 104 receives the 5 conductors or wires fromtransducer assembly 702. That is, transducers 804 may be coupled toconnector 522, which includes 5 pins.

In an example implementation, each transducer 804 is mounted intransducer housing block 802. Transducer housings 802 may be implementedwith varied dimensions so long as each transducer housing block 802includes a transducer therein and is able to fit within musicalinstrument 106 as described herein. In one aspect, each transducerhousing block 802 may include an aperture in which each transducer 804may be pressed-fitted and glued or otherwise secured.

In the example, transducer housings 802 are coupled to I-connectors 610so transducer housings 802 are facing each other. That is, the secondarycoils 808 of each transducer housing, in the example, inwardly faces theother. The two humbucking microphone capsules face inward towards oneanother.

In one or more examples, each transducer housing block 802 may include abody portion to which each transducer 804 is mounted. The body portionmay be flanked by edges 810 formed of a higher density material ofgreater weight than the body portion. The edges 810 add mass to thetransducer housings 802 thereby lowering the resonant frequency oftransducer assembly 702. In one example, the resonant frequency islowered to a frequency that is inaudible by a human being, e.g., belowthe lowest audible frequency heard by human beings.

In the example of FIG. 8 , inner cords 704 may couple to edges 810through a clamping action as shown where an edge plate 812 may besecured and tightened down against edges 810 to secure inner cords 704.The other edge of inner cords 704 may extend through the apertures ofedges 614 of I-connectors 610. In an example implementation, the innersuspension system may include the I-connectors 610, inner cords 704, andthe connection mechanism for connecting or coupling inner cords 704 tothe transducer assembly 702 (e.g., the edges 810 and edge plate 812).

FIG. 9 illustrates an example implementation in which transducerassembly 702 is disposed within the frame structure of sound capturedevice 102. In the example of FIG. 9 , transducer assembly 702 iscapable of rotating about an axis formed of connectors 616. Once rotatedto a desired angle, connectors 616 may be tightened to hold transducerassembly 702 at the set angle. In one aspect, connectors 616 may beformed of a plurality of connectors, e.g., a connector assembly.

In accordance with the inventive arrangements described herein, usingtwo transducers 804 provides a variety of different benefits. Forexample, using two transducers 804 facilitates the cancelation ofunwanted resonance artifacts emanating from musical instrument 106. Useof two transducers 804 is capable of increasing the signal-to-noiseratio of the resulting audio output. Use of two transducers 804 iscapable of increasing the acoustic isolation between musical instrument106 and other adjacent undesired sound sources whether companioninstruments and/or environmental conditions (e.g., wind).

Similar to the acoustic isolation achieved with respect to sound capturedevice 102, use of inner cords 704 facilitates the acoustic isolation oftransducer assembly 702. Inner cords 704 ensure that transducer assembly702 does not contact any part of the frame structure of sound capturedevice 102 and/or shielding 502. Thus, transducer assembly 702 issuspended within sound capture device 102 and acoustically isolatedtherefrom. Inner cords 704 may be formed of the same or similar materialas cords 302 and tensioned so that vigorous movement of musicalinstrument 106 does not cause transducer assembly 702 to contact theframe structure of sound capture device 102 and/or shielding 502.

The dual suspension system, in reference to the use of the inner andouter suspension systems, also serves to reduce and/or eliminate certainaudio artifacts such as low frequency signals sometimes referred to as“rumble.” These low frequency signals may arise from playing musicalinstrument 106 or from vibrations transmissible via the stage, floor, orground to musical instrument 106.

In the example implementations described herein, inner cords 704 suspendtransducer housings 802 so that transducer housings 802 are capable ofmoving in the same direction as the diaphragms of transducers 804. Thismakes transducers 804 less susceptible to strong vibrations from anyother axis and effectively functions as a mechanical high-pass filter.That is, inner cords 704 effectively reduce low frequency noise that mayotherwise be present in the audio signals that are generated by soundcapture device 102.

FIG. 10 illustrates an example orientation of transducer assembly 702 asinstalled within musical instrument 106. In one aspect, the distance“D”, as illustrated in the example of FIG. 10 , separating the twotransducers 804 may be greater than or equal to the diameter of thediaphragm of the transducer. In the example of FIG. 10 , drumhead 116 isparallel with plane 1002. Axis 1006 is perpendicular to plane 1002. Inthe example of FIGS. 9 and 10 , transducer assembly 702 is oriented,e.g., rotatably positioned, so that angle α is approximately 45-degrees.That is, transducer housings 802 (having transducers 804 therein) arealigned on axis 1004 so that the angle formed by the axis 1004 and plane1002 is approximately 45-degrees. The angle α may be adjusted to accountfor one or more modes of vibration of drumhead 116 (e.g., the stretchedmembrane). While FIG. 10 illustrates angle α as being 45-degrees, itshould be appreciated that other values for angle α may be used and thatthe inventive arrangements described herein are not intended to belimited to such angles. Rather, angle α may be lower or higher than45-degrees. The example implementations described herein allow angle αto be adjustable. For example, the angle α may have an angle that isgreater than 0° and less than 90°.

Sound capture system 100 and, more particularly, sound capture device102 with the configuration described in connection with FIGS. 9-10 , iscapable of accurately capturing various modes of vibration that arecharacteristic of certain stretched membrane percussion instruments. Thetransducer assembly 702, for example, may be oriented as illustrated inFIG. 10 to more accurately capture various vibrational modes of musicalinstrument 106 that characterize the sound emanating from the musicalinstrument 106.

In one aspect, the rotation of transducer assembly 702, as described inconnection with FIG. 10 , allows transducer assembly 702 to moreaccurately capture the respective amplitudes of the fundamental andfirst two overtones (e.g., harmonics) generated by musical instrument106. In some cases, positioning transducer assembly 702 parallel todrumhead 116 (e.g., angle α=0° or 180°) or perpendicular to drumhead 116(angle α=90° or 270°), results in the fundamental and/or one or more ofthe overtones having different amplitude relationships among themselvesthan is the case when capturing the sound of the musical instrument 106using an external microphone and as heard by a human being.

The positioning of transducer assembly 702 also contributes to theremoval of an unwanted interior resonance of musical instrument 106referred to as the “Helmholtz resonance” that may be present. TheHelmholtz resonance refers to a low frequency note developed in the caseof a tubular instrument that is closed on one end (e.g., a stretchedmembrane percussion instrument).

FIGS. 11A, 11B, and 11C illustrate different modes of vibration of astretched membrane percussion instrument that the inventive arrangementsare adapted to capture. The different modes of vibration illustrated inFIGS. 11A, 11B, and 11C often characterize the movement of the stretchedmembrane of a percussion instrument when a user or musician appliesdifferent strokes while playing. FIG. 11A illustrates mode (0,1). FIG.11B illustrates mode (1,1). FIG. 11C illustrates mode (2,1). Thestretched membrane of a percussion instrument may have movement thatcoincides with one or more modes of vibration as illustrated in FIGS.11A, 11B, and 11C as well as more complex modes of vibration notillustrated in FIGS. 11A, 11B, and 11C. Transducer assembly 702, aspositioned in sound capture device 102, is capable of accuratelycapturing one or more of the various modes of vibration thatcharacterize the sound of a stretched membrane percussion instrument.

Having described sound capture device 102 and other hardware thatfacilitates suspension of sound capture device 102 within musicalinstrument 106, the following discussion provides additional informationconcerning the positioning of sound capture device 102 within musicalinstrument 106. In terms of vertical positioning, the distance fromdrumhead 116 to the existing musical instrument hardware to which soundcapture device 102 is suspended may vary from one musical instrument toanother. For example, the top lug bolt of a first drum may beapproximately 5.5″ from the drumhead, while the top lug bolt of a seconddrum may be approximately 5.375″ away from the drumhead. Differentmanufacturers may vary widely in this regard. The adjustability of theC-mount 220 with respect to the universal mounting plate 218 accountsfor this variability allowing sound capture device 102 to be positionedat a uniform distance or a desired distance from drumhead 116 indifferent sized percussion instruments.

In determining the vertical position of sound capture device 102, e.g.,the distance from drumhead 116 to sound capture device 102, severaldifferent factors may be considered. These factors can include, but arenot limited to, signal gain, the so called “Barreto” test previouslydescribed, and sympathetic resonance. Sympathetic resonance refers tothe phenomenon where a drumhead such as drumhead 116 is not activated bytouch, but rather by the sound emanating from, or generated by, anotherdrum proximate thereto.

With respect to signal gain, the smaller the distance between soundcapture device 102 and drumhead 116, the higher the sound pressure level(SPL) and, as such, the larger the signal gain produced by sound capturedevice 102. Correspondingly, the larger the distance between soundcapture device 102 and drumhead 116, the lower the SPL and the lower thesignal gain produced by sound capture device 102. Larger distances alsoallow a greater opportunity for unwanted noise to be detected by soundcapture device 102. Unwanted noise or unwanted signals may include, butare not limited to, interior resonances, low frequency rumble, andambient noise. The distance between sound capture device 102 anddrumhead 116 may be adjusted to increase the signal-to-noise ratio.

The suspension system(s) described herein allow sound capture device102, inclusive of the transducer assembly 702, to be suspended withinmusical instrument 106 so that vigorous shaking of musical instrument106 does not generate unwanted audio artifacts from sound capture device102 contacting any of the various surfaces described. That is, soundcapture device 102 is suspended from universal mounting assembly 212 soas to prevent contact between sound captured device 102 and innersurface 202 of shell 114. Similarly, the transducer assembly 702 issuspended within the frame structure of sound capture device 102 so asto prevent the transducer assembly 702 from contacting the components ofthe frame structure of sound capture device 102 and/or the shielding502.

The example implementations described herein provide improved isolationin terms of detection of other sound sources. As an illustrative andnon-limiting example, two hand drums may be placed next to, or adjacentto, one another. Within the first of the hand drums, sound capturedevice 102 is suspended therein substantially as described herein. Forpurposes of comparison, a conventional microphone may be locatedexternal to the first hand drum such that a strike to the first handdrum results in each of sound capture device 102 and the conventionalmicrophone generating substantially equivalent amplitudes in theresulting audio signal. If the second hand drum is struck, the amplitudeof the strike to the second hand drum, as detected by sound capturedevice 102 in the first hand drum, is lower or reduced compared to theamplitude of the strike to the second hand drum as detected by theconventional microphone.

In scenarios where the conventional microphone is disposed inside of thefirst hand drum, the isolation performance of the conventionalmicrophone tends to become worse than when placed external to the firsthand drum and pointing to the drumhead of the first hand drum. That is,the amplitude of the signal from a strike of the second hand drum, asdetected by a conventional microphone mounted within the first hand drumis larger than the amplitude of the signal from a strike of the secondhand drum when the conventional microphone is mounted external to thefirst hand drum as previously described.

The vertical positioning of sound capture device 102 within musicalinstrument 106 influences the performance of sound capture device 102 interms of the detection of sympathetic resonance within the resultingaudio signal. That is, the closer sound capture device 102 is todrumhead 116, the more sound capture device 102 detects sympatheticresonance and the greater the presence of sympathetic resonance in theresulting audio signal. The farther sound capture device 102 fromdrumhead 116, the less sound capture device 102 is able to detectsympathetic resonance such that sympathetic resonance has a lesserpresence in the resulting audio signal.

It should be appreciated that certain percussion instruments, e.g.,congas, have a natural sympathetic resonance that occurs by virtue ofacoustics between the drums. For example, given a pair of hand drumsplaced adjacent to one another, if the first hand drum is struck, onewill hear the fundamental of the first hand drum when placing one's earnext to the second hand drum. The inventive arrangements describedherein are not intended to mitigate and/or eliminate all such naturallyoccurring sympathetic resonances and can be configured to capture thesame amount of naturally occurring sympathetic resonance as compared toan external microphone.

The horizontal positioning of sound capture device 102 within musicalinstrument 106 may be determined by a variety of factors. One factor isthat the transducers within sound capture device 102 are preferablyoffset from a center of drumhead 116 to accurately represent the timbreof musical instrument 106. Another factor is that the offset preferablyis set to leave sufficient space between sound capture device 102 andthe inner surface 202 of the shell 114 of musical instrument 106.Sufficient space ensures that sound capture device 102 does not contactthe inner surface 202 of shell 114 during rigorous performance or intransport.

FIGS. 12A and 12B illustrate examples of diffusor 112. In the example ofFIG. 12A, diffusor 112 has a body portion implemented as a hollowcylindrical structure. Diffusor 112 is shown removed from musicalinstrument 106 for purposes of illustration. Diffusor 112 may be held inplace within musical instrument 106 using prongs 1202, where the end ofeach prong 1202 may have a foot 1204. The feet 1204 may be implementedusing rubber or neoprene foot, for example. In the example of FIG. 12A,the body portion of diffusor 112 is not tapered, though in other exampleimplementations, the body portion of diffusor 112 may be tapered towardthe top while in still other example implementations the body portion ofdiffusor 112 may be tapered toward the bottom.

FIG. 12B illustrates diffusor 112 positioned within musical instrument106. The view of FIG. 12B shows musical instrument 106 with drumhead 116being removed and without sound capture device 102 suspended therein toprovide a clear view of diffusor 112.

Though diffusor 112 is described as being held in place using prongs1202 and feet 1204, in other examples, diffusor 112 may be held inposition within musical instrument 106 by suspending diffusor withinmusical instrument 106. In another example, diffusor 112 may besuspended using plastic rods or another mechanism that provides acousticisolation and does not rattle (e.g., is not susceptible to physicalvibration or shaking of musical instrument 106).

FIG. 13 illustrates an exploded view of sound capture system 100 andmusical instrument 106. In the example, sound capture system 100 isshown including sound capture device 102, signal processing circuit 104,and diffusor 112. Audio connector 130 is also shown along with C-mount220 and the universal mounting assembly 212. In the example of FIG. 13 ,it should be appreciated that the diffusor 112 may be installed from thetop of the musical instrument and is illustrated below for purposes ofillustration.

FIG. 14 illustrates an example circuit architecture for signalprocessing circuit 104. In the example of FIG. 14 , signal processingcircuit 104 includes a preamplifier circuit 1402, a channel mixer 1472,a filter circuit 1410, an audio output circuit 1412, a transformer 1438,and a power supply 1450. The various circuit blocks illustrated in FIG.14 are capable of processing signals, as described, in real time. In theexample of FIG. 14 , the phantom power source 1460 represents anexternal device capable of supplying phantom power. That is, phantompower source 1460 is shown for purposes of illustration but is not partof signal processing circuit 104. For example, phantom power source 1460may be a console into which signal processing circuit 104 is connected.

Preamplifier circuit 1402 may be implemented as a two-channelpreamplifier. Each channel, shown as channels 1 and 2, of preamplifiercircuit 1402 receives the signals generated by one of the twotransducers 804 of sound capture device 102. For example, channel 1receives positive signal 1414 and negative signal 1416 from thetransducer 804 that is rotated to a position closest to drumhead 116.Channel 2 of preamplifier circuit 1402 receives the positive signal 1418and the negative signal 1420 from transducer 804 that is rotated to aposition that is farthest from drumhead 116. A ground signal 1422 thatis coupled to the shielding of sound capture device 102, e.g., shielding502, is coupled to ground of preamplifier circuit 1402.

In one or more examples, preamplifier circuit 1402 may be implemented asa low-noise, low current, op-amp based microphone preamplifier circuit.Preamplifier circuit 1402 is capable of buffering received signals 1414,1416, 1418, and 1420 and providing a low impedance for subsequentprocessing stages. Preamplifier circuit 1402 is also capable ofincreasing the gain of the received signals to output signals 1424, 1426with increased levels. This can improve signal-to-noise ratio of signalprocessing circuit 104.

Channel 1 is capable of outputting signal 1424 to channel mixer 1472. Inthe example, channel mixer 1472 includes a phase shift and attenuatorcircuit 1404 and a difference amplifier circuit 1408. As shown, channel1 is capable of outputting signal 1424 to phase shift and attenuatorcircuit 1404. Signal 1424 may be generated by summing signals 1414 and1416. Channel 2 outputs signal 1426 to channel mixer 1472. As shown,channel 2 outputs signal 1426 to phase shift and attenuator circuit1404. Signal 1426 may be generated by summing signals 1418 and 1420.Phase shift and attenuator circuit 1404 outputs signal 1428 to a firstinput of difference amplifier circuit 1408. Phase shift and attenuatorcircuit 1404 outputs signal 1430 to a second input of differenceamplifier circuit 1408. Difference amplifier circuit 1408 outputs signal1432 to filter circuit 1410.

Filter circuit 1410 outputs signal 1434 to audio output circuit 1412.Audio output circuit 1412 may output signal 1436 to transformer 1438.Transformer 1438 is capable of generating output signal 1452 to othersystems and routing DC power to power supply 1450. Output signal 1452may be a low impedance, balanced signal. Power supply 1450 is capable ofproviding one or more different voltage level power signals, generatedfrom phantom power source 1460 (e.g., a DC component that is present onsignal 1452 as provided from power source 1460) to power othercomponents of signal processing circuit 104. For purposes ofillustration, the one or more different voltage level power signalsgenerated by power supply 1450 are illustrated as regulated DC power out1470. Appreciably, output signal 1452 may include an AC componentcarrying the processed audio output from signal processing circuit 104.Output signal 1452 may be conveyed over a suitable audio connector suchas an XLR connector.

Phase shift and attenuator circuit 1404 receives signal 1424 fromchannel 1 of preamplifier circuit 1402 and receives signal 1426 fromchannel 2 of preamplifier circuit 1402. In one example implementation, aphase shift portion of phase shift and attenuator circuit 1404 isimplemented as a second order all pass filter. The phase shift portionof phase shift and attenuator circuit 1404 may be implemented with acenter frequency denoted as F₀. The phase shift portion of phase shiftand attenuator circuit 1404 is configured to generate signal 1428 havinga center frequency F₀ that is substantially 180 degrees out of phasewith signal 1430.

In one aspect, signal processing circuit 104, using channel mixer 1472,is operative to cancel unwanted resonances, e.g., artifacts, detected bysound capture device 102. In general, phase shift and attenuator circuit1404 phase shifts the incoming signal 1424 so that signal 1428 includescertain desired frequencies such as the fundamental and one or morenatural overtones in phase with the same frequencies of signal 1430.Certain other frequencies that are undesirable are phase-shifted to beout of phase with the same undesirable frequencies of signal 1430thereby canceling each other out by operation of difference amplifiercircuit 1408. Thus, signal 1432 includes the desirable frequencies frommusical instrument 106 such as the fundamental and one or more naturalovertones while other undesirable frequencies are removed.

In an example implementation, phase shift and attenuator circuit 1404 isoperable to phase shift frequencies approximately 180° out of phase fromthe incoming signal in the range of approximately 600-800 Hz. Thefrequency range of 600-800 Hz is characteristic of the unwantedresonances captured by sound capture device 102. The center frequency F₀may be considered a problem frequency with respect to musical instrument106 in that the center frequency F₀ may be the dominant standing wavefrequency that occurs inside musical instrument 106. In cases wheremusical instrument 106 is tubular in shape, for example, the standingwave is analogous to a room mode given the dimensions of the musicalinstrument.

In one or more embodiments, the center frequency F₀ of the phase shiftportion of phase shift and attenuator circuit 1404 may be set atapproximately 700 Hz. Appreciably, the frequency of signal 1428 at thecenter frequency of the phase shift portion of phase shift andattenuator circuit 1404 is shifted 180° from the that of incoming signal1424. Frequencies above and below the center frequency in signal 1428become increasingly in phase with the corresponding frequencies ofsignal 1424 with increasing distance from the center frequency F₀.

FIG. 15 is a graph illustrating an example of the phase curve applied bythe phase shift portion of phase shift and attenuator circuit 1404.

In one aspect, phase shift and attenuator circuit 1404 include anattenuator portion. In an example implementation, the attenutatorportion may be implemented as an active attenuator. The attenuatorportion of phase shift and attenuator circuit 1404 is configured tomatch the levels of signals 1428 and 1430 so that both signals 1428 and1430 have the same or substantially the same RMS (root-mean-square)voltage prior to entering difference amplifier circuit 1408. That is,the attenuator portion of phase shift and attenuator circuit 1404 isoperable to modify levels of one or both of signals 1428 and 1430 sothat the two signals have substantially matching signal levels.

In matching levels of signals 1428, 1430, it should be appreciated thatthe attenuator portion of phase shift and attenuator circuit 1404 may beoperable on signal 1428, or signal 1430, or on both signals 1428, 1430.Further, the attenuator portion of phase shift and attenuator circuit1404 may adjust levels of one or both of such signals by increasing thelevel of one or both signals 1428, 1430, decreasing the level of one orboth signals 1428, 1430, or increasing the level of one signal whiledecreasing the level of the other signal. Further, it should beappreciated that the attenuator portion of phase shift and attenuatorcircuit 1404 may increase (decrease) the level of signals 1428 by afirst amount and increase (decrease) the level of signal 1430 by adifferent amount than used to adjust signal 1430.

Difference amplifier circuit 1408 receives signals 1428 and 1430, whichare matched in terms of amplitude post processing by phase shift andattenuator circuit 1404. Signal 1428 may be provided to thenon-inverting input difference amplifier circuit 1408, while signal 1430may be provided to the inverting input of difference amplifier circuit1408. Signal 1432, as output by difference amplifier circuit 1408,mitigates the unwanted problem frequency, or unwanted interiorresonances, previously discussed. That is, the amplitude of the unwantedinterior resonances are reduced and/or removed through operation of thedifference amplifier circuit 1408 using phase cancelation.

FIG. 16 is a graph illustrating an example of the notched frequencyaround the center frequency that may be generated by differenceamplifier circuit 1408 (e.g., in signal 1432). The center frequency is700 Hz. The graph illustrates a diminished signal level around thecenter frequency. The graph of FIG. 16 is created using two identicalwhite noise signals as signals 1424 and 1426.

FIG. 17 illustrates an example of a spectrum analysis of the soundgenerated by a tumba conga drum as captured by a conventional microphonelocated external to the drum. For purposes of reference, the spectrumanalysis of FIG. 17 is captured by a Sennheiser MD-421.

FIG. 18 illustrates an example of a spectrum analysis of signal 1436, asoutput from audio output circuit 1412, representing the sound generatedby the tumba conga drum using only a single transducer 804. For example,only the top transducer 804 may be used as provided to channel 1 ofpreamplifier circuit 1402 without phase shifting or use of differenceamplifier circuit 1408. As illustrated, the spectrum analysis includesan unwanted resonance at approximately 700 Hz.

FIG. 19 illustrates an example of a spectrum analysis of signal 1436, asoutput from audio output circuit 1412, representing the sound generatedby the tumba conga drum using both transducers 804, phase shift andattenuator circuit 1404, and difference amplifier circuit 1408 forprocessing. FIG. 19 illustrates that the unwanted resonance is mitigatedthereby resulting in a more natural sound of the musical instrument asconveyed by signal 1436. Thus, summing signal 1428 with signal 1430 byway of difference amplifier 1408 results in signal 1432 having asignificant notch, e.g., reduction in amplitude, at the center frequencyF₀ of phase shift circuit 1404.

The signal processing technique illustrated in FIG. 14 provides anotherbenefit with respect to interior resonances. The processing describedthrough preamplifier circuit 1402, phase shift and attenuator circuit1404, and difference amplifier circuit 1408 is capable of mitigatingunwanted frequencies in the range of approximately 600-800 Hz therebyeffectively canceling the unwanted interior resonances. Becausedifferently sized musical instruments (e.g., stretched membranepercussion instruments) within a same family of musical instruments willhave different interior resonance frequencies (e.g., standing waves)within this range, the techniques illustrated and described inconnection with FIG. 14 are capable of attenuating and/or eliminatingthese unwanted interior resonances across differently sized stretchedmembrane musical instruments of a same family without furthermodification of the signal processing circuit 104. This makes thecircuit architecture illustrated in FIG. 14 suitable for use across avariety of differently sized stretched membrane percussion instrumentswithin a same family of stretched membrane percussion instrument (e.g.,from one size conga drum to another).

In addition, the unwanted frequenc(ies) to be notched for a givenstretched membrane percussion instrument may change with the particulartuning of musical instrument 106. The inventive arrangements describedherein are operable to remove unwanted interior resonances fordifferently tuned percussion instruments.

The circuit architecture described in connection with FIG. 14 is capableof attenuating and/or removing the unwanted resonance in the frequencyrange without affecting or substantially affecting the natural overtonesof musical instrument 106 while also preserving the timbre and characterof musical instrument 106. The techniques described within thisdisclosure are capable of operating in an adaptive manner thatautomatically adapts to remove the unwanted interior resonance despitethe particular frequency of the standing wave varying from one sizestretched membrane percussion instrument to another and/or tuning of thestretched membrane percussion instrument so long as the unwantedresonance is within the defined frequency range.

Otherwise, were an equalization notch filter to be used in place of thecircuit architecture of FIG. 14 , an analysis of each differently sizedstretched membrane percussion instrument would be necessary in order toconfigure or tune the equalization notch filter for attenuation of thedesired frequencies within each respective musical instrument. Further,the equalization notch filter, despite tuning for each differently sizedinstrument within a given family, does affect or substantially affectthe natural overtones, timbre, and character of musical instrument 106.

Filter circuit 1410 may be included to boost and/or cut one or morefrequency ranges in the signal output from difference amplifier circuit1408. In the example of FIG. 14 , the constituent filters of filtercircuit 1410 are connected in serial. Filter circuit 1410 may includehigh-pass filter circuit 1440, high-frequency boost filter circuit 1442,and mid-frequency boost filter circuit 1444.

High pass filter circuit 1440 may be included to reduce low frequencyrumble, e.g., low frequency artifacts at or about 80 Hz and below, inthe signal. High-pass filter circuit 1440 generates signal 1446, whichis provided as an input to high-frequency boost filter circuit 1442. Inone or more example implementations, high-pass filter circuit 1440 isoptional and may omitted from filter circuit 1410.

High-frequency boost filter circuit 1442 is operative to increase thesignal-to-noise ratio in the higher frequencies of the audible spectrum.In an example implementation, the high-frequency boost filter circuit1442 is operable to increase or accentuate frequencies in the range ofapproximately 3 kHz to 10 kHz. High-frequency boost filter circuit 1442is capable of adding gain to the noted frequency range prior to thesignal generated from sound capture system 100 being processed furtherthrough other active circuits such as a mixing console. Adding gain tothe noted frequency range earlier in the signal chain may help to reducehigh frequency hiss that is often added by further active circuitsattempting to increase this frequency range later in the signal chain.

For example, sound engineers often increase this frequency range forpercussion instruments to accentuate the attack. By boosting suchfrequencies earlier in the signal chain, the amount of high frequencyhiss or noise added to the signal from further boosting the 3 kHz to 10kHz frequency range later in the signal chain may be reduced.High-frequency boost filter circuit 1442 generates signal 1448, which isprovided to mid-frequency boost filter circuit 1444 as an input.

Mid-frequency boost filter circuit 1444 is capable of boosting orincreasing the frequencies in the range of F₀ as operated on by phaseshift circuit 1404. The mid-frequency boost filter circuit 1444 may beused to compensate for cases where the frequency F₀ is reduced more thandesired by difference amplifier circuit 1408. Mid-frequency boost filtercircuit 1444 generates signal 1434, which may be provided to audiooutput circuit 1412.

Audio output circuit 1412 receives signal 1434 post filtering by filtercircuit 1410. Audio output circuit 1412 is capable of outputting signal1436 as a microphone level signal as is generated and output from any ofa variety of standard passive dynamic microphones. Examples of passivedynamic microphones include, but are not limited to, Shure SM57,Sennheiser MD-421 as are commonly used with percussion instruments.

Audio output circuit 1412 generates signal 1436, which is provided totransformer 1438 as an input. Transformer 1438 generates signal 1452.Transformer 1438 is capable of providing the low impedancecharacteristics of a dynamic microphone output. Transformer 1438 andother active stages of signal processing circuit 104 are designed tomatch the voltage (gain) levels of a “mic level” device. Transformer1438 further helps isolate the DC component from phantom power source1460 and prevent the DC component from entering the AC signal path thatperforms the AC real-time processing. Transformer 1438 is capable ofdirecting the DC component to power supply 1450.

Use of the transformer 1438 also helps to maintain low current and lownoise circuit performance. Other circuit architectures, e.g., an active(e.g., op-amp) output stage driving a low impedance load with low noise,would generally require more current than is available from phantompower source 1460.

In one aspect, signal 1452 includes the processed audio as the ACcomponent. The DC component provided by phantom power source 1460 can beprovided to power supply 1450. As noted, power supply 1450 is capable ofproviding one or more different voltage level power signals shown asregulated DC power out 1470 to power the other components of signalprocessing circuit 104.

In the examples, the signal path through signal processing circuit 104consumes little power and utilizes low noise audio op-amps to performthe functions performed by preamplifier circuit 1402, phase shiftcircuit 1404, channel mixer and attenuator circuit 1406, differenceamplifier circuit 1408, and filter circuit 1410. These stages may alsooperate at 48-volts. Transformer 1438 therein, is capable of attenuatingthe signal down to “microphone level.” For example, transformer 1438 iscapable of stepping down the output level (e.g., voltage) of signal 1436to that of a microphone level signal and also lowers the outputimpedance of the signal processing circuit 104. Transformer 1438 is alsocapable of isolating output from certain components such as op-amps fromthe DC component provided from phantom power source 1460 and reducingthe load on the op-amps.

In the example of FIG. 14 , the 48-volt phantom power is used to powersignal processing circuit 104 and not for operation of sound capturedevice 102. In one or more example implementations, regulated DC poweroutput 1470 may be provided to active components included in signalprocessing circuit 104. The active components may include preamplifiercircuit 1402, phase shift circuit 1404, channel mixer and attenuatorcircuit 1406, and/or difference amplifier circuit 1408. The inventivearrangements allow signal processing circuit 104 to be powered byphantom power source 1460 thereby negating the need for anotherindependent power source.

In one or more other arrangements, however, power supply 1450 may obtainpower from another source such as an external AC power adapter (e.g.,wall wart power supply), battery source, or the like. In that case, useof phantom power is not necessary.

FIG. 20 is a block diagram illustrating an example of the connectivitybetween sound capture device 102 and the signal processing circuit 104.In the example, the transducers 804 are coupled to signal processingcircuit 104 by way of multi-pin connector 522. Multi-pin connector 522is implemented as a 5-pin connector in the example. The output fromsignal processing circuit 104 may be provided to other devices by way ofaudio connector 130. Audio connector 130 may be a 3-pin female XLRconnector providing signal 1452 (e.g., as ground, positive, and negativesignals or shield, hot, and cold signals, respectively).

FIG. 21 is a circuit diagram illustrating an example implementation ofthe preamplifier circuit 1402. In one or more example implementations,the circuit components for channels 1 and 2 of the preamplifiercircuitry may be specified as follows.

-   -   C1: 220 pF    -   C2: 220 pF    -   C3: 1 uF    -   C4: 1 uF    -   C5: 100 pF    -   C6: 0.1 uF    -   C7: 1 uF    -   C8: 22 pF    -   C9: 22 pF    -   R1: 100 kΩ    -   R2: 100 kΩ    -   R3: 6.81 kΩ    -   R4: 20 kΩ    -   R5: 20 kΩ    -   R6: 75 Ω    -   R7: 75 Ω    -   R8: 28 Ω    -   R9: 28 Ω    -   R10: 10 kΩ    -   R11: 10 kΩ    -   R12: 10 kΩ    -   R13: 10 kΩ

FIG. 22 is a circuit diagram illustrating an example implementation ofphase shift and attenuator circuit 1404, difference amplifier circuit1408, and the high-pass filter circuit 1440. The signal referencenumbers illustrate the demarcation between the respective circuitblocks. In one or more example implementations, the circuit componentsof the example of FIG. 22 may be specified as follows.

-   -   C1: 0.1 uF    -   C2: 1 uF    -   C3: 0.015 uF    -   C4: 0.015 uF    -   C5: 22 pF    -   C6: 0.1 uF    -   C7: 1 uF    -   C8: 22 pF    -   C9: 0.47 uF    -   C10: 0.47 uF    -   R1: 3.83 kΩ    -   R2: 15 kΩ    -   R3: 15 kΩ    -   R4: 15 kΩ    -   R5: 3.83 kΩ    -   R6: 5.62 kΩ    -   R7: 10 kΩ    -   R8: 10 kΩ    -   R9: 10 kΩ    -   R10: kΩ    -   R11: 8.25 kΩ    -   R12: 15.8 kΩ

FIG. 23 is a circuit diagram illustrating an example implementation ofthe high-frequency boost filter circuit 1442 and the mid-frequency boostfilter circuit 1444. In one or more example implementations, the circuitcomponents for the example of FIG. 23 may be specified as follows.

-   -   R1: 10 kΩ    -   R2: 10 kΩ    -   R3: 11.5 kΩ    -   R4: 11.5 kΩ    -   R5: 5.76 kΩ    -   R6: 3.09 kΩ    -   R7: 10 kΩ    -   R8: 10 kΩ    -   R9: 7.15 kΩ    -   R10: 7.15 kΩ    -   R11: 4.87 kΩ    -   R12: 9.09 kΩ    -   C1: 0.1 uF    -   C2: 1 uF    -   C3: 22 pF    -   C4: 0.0047 uF    -   C5: 0.0047 uF    -   C6: 0.1 uF    -   C7: 1 uF    -   C8: 22 pF    -   C9 0.068 uF    -   C10: 0.033 uF

FIG. 24 is a circuit diagram illustrating an example implementation ofthe audio output circuit 1412. In one or more example implementations,the circuit components for the example of FIG. 24 may be specified asfollows.

-   -   R1: 100 Ω    -   R2: 10 kΩ    -   R3: 10 kΩ    -   R4: 10 kΩ    -   R5: 100 kΩ    -   R6: 100 kΩ    -   R7: 100 Ω    -   R8: 100 Ω    -   Variable Resistor: 10 kΩ, Value=50    -   C1: 0.1 uF    -   C2: 1 uF    -   C3: 22 pF    -   C4: 100 uF    -   C5: 1 uF    -   C6: 100 uF    -   C7: 1 uF

FIG. 25 is a circuit diagram illustrating an example of a power supply1450 described in connection with FIG. 14 . In one or more exampleimplementations, the circuit components for the example of FIG. 25 maybe specified as follows.

-   -   R1: 6.81 kΩ    -   R2: 6.81 kΩ    -   R3: 1 kΩ    -   R4: 1 kΩ    -   R5: 10 kΩ    -   R6: 15 kΩ    -   R7: 8.66 kΩ    -   R8: 100 Ω    -   R9: 150 kΩ    -   R10: 150 kΩ    -   Variable Resistor: 100 kΩ, value=55    -   C1: 1500 uF    -   C2: 4.7 uF    -   C3: 4.7 uF    -   C4: 1 uF    -   C5: 0.1 uF    -   C6: 1 uF

FIG. 26 is a circuit diagram illustrating examples of audio outputcircuit 1412 and transformer 1438 in relation to power supply 1450 asdescribed in connection with FIG. 14 .

FIG. 27 illustrates another example implementation of selectedcomponents of signal processing circuit 104. In the example of FIG. 27 ,the various circuit blocks illustrated in FIG. 14 such as phase shiftcircuit 1404, channel mixer and attenuator circuit 1406, differenceamplifier circuit 1408, and filter circuit 1410, may be implementedusing program code executable by a processor such as a digital signalprocessor that may be included in a data processing system.

Accordingly, FIG. 27 illustrates an example of other circuitry embodiedas a data processing system that may be used to implement the phaseshift circuit 1404, channel mixer and attenuator circuit 1406,difference amplifier circuit 1408, and filter circuit 1410 of the signalprocessing circuit 104 as executable program code (e.g., software)executed using suitable hardware. Like the example implementation ofFIG. 14 , the example of FIG. 27 is capable of performing the operationsdescribed in connection with FIG. 14 in real time. As defined herein,“data processing system” means one or more hardware systems configuredto process data, each hardware system including at least one processorprogrammed to initiate operations and memory.

The components of data processing system 2700 can include, but are notlimited to, a processor 2702, a memory 2704, and a bus 2706 that couplesvarious system components including memory 2704 to processor 2702.Processor 2702 may be implemented as one or more processors capable ofcarrying out instructions contained in program code. The circuit may bean integrated circuit or embedded in an integrated circuit. Processor2702 may be implemented using a complex instruction set computerarchitecture (CISC), a reduced instruction set computer architecture(RISC), a vector processing architecture, a Digital Signal Processor, aGraphics Processing Unit, a programmable integrated circuit (e.g., aField Programmable Gate Array), System-on-Chip, Central Processing Unit(CPU), or other known architectures. Example processors include, but arenot limited to, processors having an x86 type of architecture (IA-32,IA-64, etc.), Power Architecture, ARM processors, and the like.

Bus 2706 represents one or more of any of a variety of communication busstructures. By way of example, and not limitation, bus 2706 may beimplemented as a Peripheral Component Interconnect Express (PCIe) bus.Data processing system 2700 typically includes a variety of computersystem readable media. Such media may include computer-readable volatileand non-volatile media and computer-readable removable and non-removablemedia.

Memory 2704 can include computer-readable media in the form of volatilememory, such as random-access memory (RAM) 2708 and/or cache memory2710. Data processing system 2700 also can include otherremovable/non-removable, volatile/non-volatile computer storage media.By way of example, storage system 2712 can be provided for reading fromand writing to a non-removable, non-volatile magnetic and/or solid-statemedia (not shown and typically called a “hard drive”). Although notshown, a magnetic disk drive for reading from and writing to aremovable, non-volatile magnetic disk (e.g., a “floppy disk”), and anoptical disk drive for reading from or writing to a removable,non-volatile optical disk such as a CD-ROM, DVD-ROM or other opticalmedia can be provided. In such instances, each can be connected to bus2706 by one or more data media interfaces. Memory 2704 is an example ofat least one computer program product.

Program/utility 2714, having a set (at least one) of program modules2716, may be stored in memory 2704. Program/utility 2714 is executableby processor 2702. By way of example, program modules 2716 may representan operating system (optional), one or more application programs, otherprogram modules, and program data. Program modules 2716, upon execution,cause data processing system 2700, e.g., processor 2702, to carry outthe functions and/or methodologies of the example implementationsdescribed within this disclosure. For example, one or more programmodules 2716, when executed, may implement the various operations ofsignal processing circuit 104 as described herein.

Program/utility 2714 and any data items used, generated, and/or operatedupon by data processing system 2700 are functional data structures thatimpart functionality when employed by data processing system 2700. Asdefined within this disclosure, the term “data structure” means aphysical implementation of a data model's organization of data within aphysical memory. As such, a data structure is formed of specificelectrical or magnetic structural elements in a memory. A data structureimposes physical organization on the data stored in the memory as usedby an application program executed using a processor.

Data processing system 2700 may include one or more Input/Output (I/O)interfaces 2718 communicatively linked to bus 2706. I/O interface(s)2718 allow data processing system 2700 to communicate with one or moreexternal devices and/or communicate over one or more networks such as alocal area network (LAN), a wide area network (WAN), and/or a publicnetwork (e.g., the Internet). Examples of I/O interfaces 2718 mayinclude, but are not limited to, network cards, modems, networkadapters, hardware controllers, etc. Examples of external devices alsomay include devices that allow a user to interact with data processingsystem 2700 (e.g., a display, a keyboard, and/or a pointing device)and/or other devices such as accelerator card.

In another example implementation, I/O interfaces 2718 may include ananalog-to-digital converter (ADC) configured to generate digitized data,e.g., samples, from analog signals received from preamplifier circuit1402. I/O interfaces 2718 may also include a digital-to-analog converter(DAC) configured convert digital data, e.g., samples, into analogsignals that may be provided to one or more other systems such as audiooutput circuit 1412. It should be appreciated that in one or more otherexample implementations, data processing system 2700 may output digitaldata, e.g., samples, subsequent to the processing described withreference to FIG. 14 to one or more other compatible (e.g., digital)sound processing devices or systems.

Data processing system 2700 is only one example implementation. Dataprocessing system 2700 can be practiced as a standalone device (e.g., asa computer), as a System-on-Chip, or other form factor. The example ofFIG. 27 is not intended to suggest any limitation as to the scope of useor functionality of example implementations described herein. Dataprocessing system 2700 is an example of computer hardware that iscapable of performing the various operations described within thisdisclosure. In this regard, data processing system 2700 may includefewer components than shown or additional components not illustrated inFIG. 27 depending upon the particular type of device and/or system thatis implemented.

FIG. 28 illustrates an example method 2800 for a sound capture system inaccordance with the inventive arrangements described herein. Method 2800may begin in block 2802 where a sound capture device configured forplacement within a sound-generating device is provided. In block 2804, asuspension system configured to suspend the sound capture device withinthe sound-generating device is provided. The suspension system iscapable of acoustically decoupling the sound capture device from thesound-generating device. The sound capture device can include aplurality of transducers configured to generate a plurality of audiosignals concurrently from sound generated by the sound-generatingdevice.

The foregoing and other implementations can each optionally include oneor more of the following features, alone or in combination. Some exampleimplementations include all the following features in combination.

The method can include providing a signal processing circuit configuredto receive the plurality of audio signals and generate an output audiosignal from the plurality of audio signals.

In another aspect, the signal processing circuit includes a processorprogrammed to initiate executable operations.

The method can include providing a diffusor within the sound-generatingdevice.

The method can include installing the sound capture device within amusical instrument.

The installing retrofits the sound capture device to the musicalinstrument.

The method can include installing the sound capture device and thesignal processing circuit within the musical instrument.

FIG. 29 illustrates an example method 2900 illustrating certainoperative features of the inventive arrangements described herein. FIG.29 illustrates certain operations implemented by sound capture system100 including sound capture device 102 and signal processing circuit104.

In block 2902, a first differential signal 1414, 1416 can be generatedfrom a first transducer 804 disposed in a musical instrument 106. Inblock 2904, a second differential signal 1418, 1420 can be generatedfrom a second transducer 804 disposed in the musical instrument 106. Inblock 2906, a first composite signal 1424 can be generated from thefirst differential signal. In block 2908, a second composite signal 1426can be generated from the second differential signal. In block 2910, thefirst composite signal and the second composite signal can be signalprocessed using signal processing circuitry to generate an audio outputsignal 1452 by, at least in part, taking a difference between the firstcomposite signal and the second composite signal (e.g., using differenceamplifier circuit 1408).

The foregoing and other implementations can each optionally include oneor more of the following features, alone or in combination. Some exampleimplementations include all the following features in combination.

In another aspect, the signal processing can include filtering adifference signal 1432 generated by the taking a difference between thefirst composite signal and the second composite signal using one or morefilter circuits.

In another aspect, the method can include providing power (regulated DCpower output 1470) to one or more active components of signal processingcircuit 104 configured to perform the signal processing, wherein thepower is derived from phantom power source 1460.

As defined herein, the singular forms “a,” “an,” and “the” are intendedto include the plural forms as well, unless the context clearlyindicates otherwise.

As defined herein, the term “approximately” means nearly correct orexact, close in value or amount but not precise. For example, the term“approximately” may mean that the recited characteristic, parameter, orvalue is within a predetermined amount of the exact characteristic,parameter, or value.

As defined herein, the terms “at least one,” “one or more,” and“and/or,” are open-ended expressions that are both conjunctive anddisjunctive in operation unless explicitly stated otherwise. Forexample, each of the expressions “at least one of A, B, and C,” “atleast one of A, B, or C,” “one or more of A, B, and C,” “one or more ofA, B, or C,” and “A, B, and/or C” means A alone, B alone, C alone, A andB together, A and C together, B and C together, or A, B and C together.

As defined herein, the term “automatically” means without humanintervention. As defined herein, the term “user” means a human being.

As defined herein, the term “computer readable storage medium” means astorage medium that contains or stores program code for use by or inconnection with an instruction execution system, apparatus, or device.As defined herein, a “computer readable storage medium” is not atransitory, propagating signal per se. A computer readable storagemedium may be, but is not limited to, an electronic storage device, amagnetic storage device, an optical storage device, an electromagneticstorage device, a semiconductor storage device, or any suitablecombination of the foregoing. The various forms of memory, as describedherein, are examples of computer readable storage media. Anon-exhaustive list of more specific examples of a computer readablestorage medium may include: a portable computer diskette, a hard disk, aRAM, a read-only memory (ROM), an erasable programmable read-only memory(EPROM or Flash memory), an electronically erasable programmableread-only memory (EEPROM), a static random-access memory (SRAM), aportable compact disc read-only memory (CD-ROM), a digital versatiledisk (DVD), a memory stick, a floppy disk, or the like.

As defined herein, the term “if” means “when” or “upon” or “in responseto” or “responsive to,” depending upon the context. Thus, the phrase “ifit is determined” or “if [a stated condition or event] is detected” maybe construed to mean “upon determining” or “in response to determining”or “upon detecting [the stated condition or event]” or “in response todetecting [the stated condition or event]” or “responsive to detecting[the stated condition or event]” depending on the context.

As defined herein, the term “responsive to” and similar language asdescribed above, e.g., “if,” “when,” or “upon,” means responding orreacting readily to an action or event. The response or reaction isperformed automatically. Thus, if a second action is performed“responsive to” a first action, there is a causal relationship betweenan occurrence of the first action and an occurrence of the secondaction. The term “responsive to” indicates the causal relationship.

As defined herein, the term “real time” means a level of processingresponsiveness that a user or system senses as sufficiently immediatefor a particular process or determination to be made, or that enablesthe processor to keep up with some external process.

As defined herein, the term “substantially” means that the recitedcharacteristic, parameter, or value need not be achieved exactly, butthat deviations or variations, including for example, tolerances,measurement error, measurement accuracy limitations, and other factorsknown to those of skill in the art, may occur in amounts that do notpreclude the effect the characteristic was intended to provide.

The terms first, second, etc. may be used herein to describe variouselements. These elements should not be limited by these terms, as theseterms are only used to distinguish one element from another unlessstated otherwise or the context clearly indicates otherwise.

A computer program product may include a computer readable storagemedium (or media) having computer readable program instructions thereonfor causing a processor to carry out aspects of the inventivearrangements described herein. Within this disclosure, the term “programcode” is used interchangeably with the term “computer readable programinstructions.” Computer readable program instructions described hereinmay be downloaded to respective computing/processing devices from acomputer readable storage medium or to an external computer or externalstorage device via a network, for example, the Internet, a LAN, a WANand/or a wireless network. The network may include copper transmissioncables, optical transmission fibers, wireless transmission, routers,firewalls, switches, gateway computers and/or edge devices includingedge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations forthe inventive arrangements described herein may be assemblerinstructions, instruction-set-architecture (ISA) instructions, machineinstructions, machine dependent instructions, microcode, firmwareinstructions, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language and/or procedural programming languages.Computer readable program instructions may include state-setting data.The computer readable program instructions may execute entirely on theuser's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough any type of network, including a LAN or a WAN, or the connectionmay be made to an external computer (for example, through the Internetusing an Internet Service Provider). In some cases, electronic circuitryincluding, for example, programmable logic circuitry, an FPGA, or a PLAmay execute the computer readable program instructions by utilizingstate information of the computer readable program instructions topersonalize the electronic circuitry, in order to perform aspects of theinventive arrangements described herein.

Certain aspects of the inventive arrangements are described herein withreference to flowchart illustrations and/or block diagrams of methods,apparatus (systems), and computer program products. It will beunderstood that each block of the flowchart illustrations and/or blockdiagrams, and combinations of blocks in the flowchart illustrationsand/or block diagrams, may be implemented by computer readable programinstructions, e.g., program code.

These computer readable program instructions may be provided to aprocessor of a computer, special-purpose computer, or other programmabledata processing apparatus to produce a machine, such that theinstructions, which execute via the processor of the computer or otherprogrammable data processing apparatus, create means for implementingthe functions/acts specified in the flowchart and/or block diagram blockor blocks. These computer readable program instructions may also bestored in a computer readable storage medium that can direct a computer,a programmable data processing apparatus, and/or other devices tofunction in a particular manner, such that the computer readable storagemedium having instructions stored therein comprises an article ofmanufacture including instructions which implement aspects of theoperations specified in the flowchart and/or block diagram block orblocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operations to be performed on the computer, otherprogrammable apparatus or other device to produce a computer implementedprocess, such that the instructions which execute on the computer, otherprogrammable apparatus, or other device implement the functions/actsspecified in the flowchart and/or block diagram block or blocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousaspects of the inventive arrangements. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified operations.

In some alternative implementations, the operations noted in the blocksmay occur out of the order noted in the figures. For example, two blocksshown in succession may be executed substantially concurrently, or theblocks may sometimes be executed in the reverse order, depending uponthe functionality involved. In other examples, blocks may be performedgenerally in increasing numeric order while in still other examples, oneor more blocks may be performed in varying order with the results beingstored and utilized in subsequent or other blocks that do notimmediately follow. It will also be noted that each block of the blockdiagrams and/or flowchart illustration, and combinations of blocks inthe block diagrams and/or flowchart illustration, may be implemented byspecial purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

1-47. (canceled)
 48. A system, comprising: a sound capture deviceconfigured for placement within a sound-generating device; and asuspension system configured to suspend the sound capture device withinthe sound-generating device and acoustically decouple the sound capturedevice from the sound-generating device; wherein the sound capturedevice includes therein a plurality of transducers coupled to aninterior of the sound capture device, the plurality of transducersconfigured to generate a plurality of audio signals concurrently. 49.The system of claim 48, wherein the sound capture device comprises aframe structure encompassing the plurality of transducers.
 50. Thesystem of claim 48, wherein the sound-generating device is a percussioninstrument comprising a stretched membrane.
 51. The system of claim 48,wherein the suspension system suspends the sound capture device withinthe sound-generating device using a plurality of flexible or stretchablecords.
 52. The system of claim 48, comprising: a diffusor positionedbelow the sound capture device and within the sound-generating device,wherein the diffusor comprises a hollow body suspended within the soundgenerating device preventing the hollow body from contacting an innersurface of the sound-generating device.
 53. The system of claim 48,further comprising: a transducer assembly coupled to the interior of thesound capture device, wherein the transducer assembly includes aplurality of transducers suspended therefrom.
 54. The system of claim53, wherein the transducer assembly is rotatably coupled to the interiorof the sound capture device.
 55. The system of claim 53, wherein theplurality of transducers is suspended from the transducer assembly usinga plurality of flexible or stretchable cords.
 56. The system of claim53, wherein each transducer of the plurality of transducers is, assuspended from the transducer assembly, acoustically isolated from thetransducer assembly.
 57. The system of claim 53, wherein the transducerassembly is configured to separate a first transducer of the pluralityof transducers and a second transducer of the plurality of transducersby a distance that is greater than or equal to a diameter of a diaphragmof one of the plurality of transducers.
 58. The system of claim 53,wherein the plurality of transducers includes a first transducer and asecond transducer each implemented as a radio-frequency noise-cancelingtransducer.
 59. The system of claim 53, wherein the plurality oftransducers includes a first transducer and a second transducer eachimplemented as a humbucking microphone capsule having a movingdiaphragm.
 60. The system of claim 59, wherein each humbuckingmicrophone capsule includes a primary coil and a secondary coil, whereinthe moving diaphragm is attached to the primary coil.
 61. The system ofclaim 60, wherein the transducer assembly is configured to position thefirst transducer and the second transducer with the secondary coilsfacing inward towards each other.
 62. The system of claim 53, whereinthe plurality of transducers includes a first transducer and a secondtransducer aligned along an axis forming an angle with a plane of astretched membrane of the sound-generating device that is greater than0° and less than 90°.
 63. A system, comprising: a sound capture deviceconfigured for placement within a sound-generating device; a firstsuspension system configured to suspend the sound capture device withinthe sound-generating device, wherein the first suspension systemacoustically decouples the sound capture device from thesound-generating device; a transducer assembly coupled to an interior ofthe sound capture device, wherein the transducer assembly comprises aplurality of transducers; and a further suspension system configured tosuspend the plurality of transducers from the transducer assembly. 64.The system of claim 63, wherein each transducer of the plurality oftransducers is, as suspended from the transducer assembly, acousticallyisolated from the transducer assembly.
 65. The system of claim 63,wherein the plurality of transducers includes a first transducer and asecond transducer each implemented as a humbucking microphone capsulehaving a moving diaphragm.
 66. The system of claim 65, wherein eachhumbucking microphone capsule includes a primary coil and a secondarycoil, wherein the moving diaphragm is attached to the primary coil. 67.A method, comprising: providing a sound capture device configured forplacement within a sound-generating device; and providing a suspensionsystem configured to suspend the sound capture device within thesound-generating device and acoustically decouple the sound capturedevice from the sound-generating device; and wherein the sound capturedevice includes therein a plurality of transducers coupled to aninterior of the sound capture device, the plurality of transducersconfigured to generate a plurality of audio signals concurrently.